To be paid $500 after a 3% fee, the invoice is $515.77, not $515

You invoice $500, the client pays through a payment service, and $484.70 arrives. So next time you add 3% and invoice $515. Now $499.25 arrives. Still short. To be paid exactly $500 after a fee of 3% plus 30 cents, the invoice has to be $515.77.

Why adding the percentage falls short

The fee is charged on whatever is paid, including the part you added to cover the fee. 3% of $515 is $15.45, not $15. Add the 30 cents and the fee is $15.75, which leaves $499.25.

The amount that works comes from dividing, not adding. Take what you want to receive, add the fixed fee, and divide by what is left of each dollar after the percentage:

($500 + $0.30) ÷ 0.97 = $515.77. The fee on that is $15.77, and $500.00 arrives.

The payment fee calculator does this for any amount and any fee. The 3% and 30 cents here are an example, not any service’s price. Read the rate for your kind of payment off the service’s own fee page.

The fixed fee is what hurts small payments

Thirty cents is nothing on $500 and a great deal on $10. The same fee takes a very different share depending on the size of the payment:

If you take many small payments, the fixed part is most of what you pay. If you take a few large ones, it disappears and the percentage is the whole cost.

A year of it

Eight invoices of $500 a month, each losing $15.30, is $122.40 a month and $1,468.80 a year. That is a real line in a small business’s costs, and it is worth knowing before setting prices.

What this leaves out

• Whether you may pass the fee on. Some services and some places restrict adding a surcharge for a payment method. That is a question for the service’s terms and local rules, not for a calculator.
• Currency conversion. A payment from abroad is usually converted at a rate with its own margin. The transfer cost calculator works that out.
• Refunds and chargebacks. These often carry fees of their own.

An estimate from example figures, not financial advice.